The Los Angeles City Council voted to build a new football stadium in the heart of downtown. The city hopes to make $13.4 million annually in taxes paid once the stadium is up and running. But sports economists say officials shouldn't be so fast to count their pennies. "There have been Lord knows how many studies of the benefits of teams and the benefits of new stadiums, and what it all comes down to is that they have essentially zero impact on a city's finances," said Mike Leeds, an economist at Temple.